1. Field of the Invention
The present invention relates to a magnetic disc system. More particularly, it relates to a magnetic disc drive system in the magnetic disc and has means for automatically determining offset correction values and a speed control gain correction value for controlling magnetic heads using the same.
2. Description of the Related Art
A magnetic disc mechanism has an offset based on the characteristics of a spring provided for restoring magnetic heads to a rest position during a stop mode. The offset is also based on the characteristics of a voice coil motor (VCM) used as an actuator for driving the magnetic heads. To realize a precise seek (speed) control and a precise position control, an offset correction must be made. The offset depends on the individual magnetic disc mechanism, and thus, before shipping a magnetic disc system, a measurement of the offset and a determination of an offset correction value must be carried out for each magnetic disc system.
A speed control gain also depends on the individual magnetic disc system, and accordingly, before shipping the magnetic disc system, a determination of an optimum speed control gain for each magnetic disc system must be carried out.
In a prior art system, the offset measurement and the offset correction value determination are manually effected, thus having the disadvantages of a troublesome manual operation and a long adjustment time. Similarly, the determination of the optimum speed control gain is manually effected, and thus also has the same disadvantages.
In addition, if a problem, which may require a replacement of parts and thus requires a repeat of the above adjustment, occurs on site, the adjustment process must be carried out at the site.
The offset of every magnetic disc mechanism depends on a radial position of the heads or cylinder position. However, in the prior art, only a single offset correction value is determined. As a result, an optimum offset correction for all cylinders cannot be achieved.